The main interest of our group is to further increase our understanding of how the higher central nervous system controls movement. The work carried out during the past year has been the continuation of that of the previous years. Shinoda, Arnold and Asanuma studied the pattern of projection from the motor cortex to the spinal cord. It is known that fibers from the pyramidal tract neurons located in a small area in the cortex do not terminate at a small area in the spinal cord although a group of motoneurons innervating a given muscle is located in a small area. The question that we asked was whether individual corticospinal neurons terminate in one and only one motoneuron pool or terminate in different motoneuron pools. Experiments were carried out in the cat by activating corticospinal neurons antidromically from various regions of the spinal cord. It was found that the majority of neurons sending axons to the cervical cord were located in the forelimb area of the motor cortex. Of these neurons, 30 percent sent branches to the lower level of the spinal cord. The remaining 70 percent sent axons only to the cervical gray matter and some of them sent multiple branches to several segments in the cervical cord. In addition, a few neurons located outside of the forelimb area sent axons to the cervical cord, but all of them also sent branches to the lower levels of the spinal cord. Neurons activated from a given area of the cervical cord tended to group together in a small area of the cortex although some of these neurons sent other branches to other parts of the spinal cord. The results suggested that activity of a given group of corticospinal neurons located in a small area of the cortex exert their influence primarily on a given motoneuron pool, but at the same time, changes excitability of other motoneuron pools.